Knowledge Center - Page 6 of 8 - Chemical Dynamics, LLC: Paint & Coatings Consultants

Considerations for Developing Wood Coatings

Wood has been used as a building material for thousands of years due to its availability, low weight to strength ratio and, in many applications, high aesthetic quality. However, as a paintable substrate, it also provides some unique challenges and considerations, as wood is a dynamic, porous (cellular structure) and hygroscopic material. A few considerations include:

Moisture content – kiln dried wood absorbs water until it reaches equilibrium with relative humidity. Moisture content can vary from about 6% to 30%.
Expansion and contraction – See Table I
Age, wood cut geometry and type of wood – (e.g. hardwood or softwood etc.) – determines paint receptivity (moderately aged wood > new wood or very old wood)

Table I – Percent Dimensional Change of Wood as Moisture Content Varies from 5 to 15%

For a 10 cm thick wood section, a fluctuation in Relative Humidity of about 10% means a change in a tangential longitudinal wood piece of 3.5 mm (or 3,500 microns). Accordingly, these relatively large dimensional changes produce cracks as the wood looses elasticity due to aging. Thus a properly designed wood coating must have the requisite flexibility to accommodate these dimensional changes without cracking. Wood is comprised of about 75% cellulose and hemicellulose and 25% lignin, resins and low molecular weight phenolics. In exterior applications, wood is susceptible to degradation and subsequent erosion due to exposure to UV degradation, oxygen, moisture and biological activity. When exposed to the elements, the lower molecular weight materials will degrade to form water-soluble compounds that wash out whereas the more stable cellulosic molecules remain to form a white-grey color.

To read the full article about Considerations for Developing Wood Coatings, click here.

Reactive Silanes for Enhancement of Coating Performance

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Reactive silanes (EU) can be used in multiple applications to enhance the performance of coatings. They can improve adhesion to inorganic substrates, provide crosslinking, improve pigment dispersion, improve hydrophobicity and scavenge moisture. A silane (EU) that contains at least one carbon silicon bond (CH3 – Si -) is called an organosilane (EU).Reactive silane is the term used to define compounds that have a trialkoxysilyl group and an alkyl group (R) containing a reactive constituent.

The trialkoxy silanes that are discussed in this article are those that contain primarily trimethoxy (EU) groups, as these molecules are the most widely used to enhance coating performance in a wide variety of applications, as follows:

Adhesion Promoter (EU)– Silanes, when added to paints, can enhance adhesion to inorganic surfaces including metals and glass.
Coupling Agent (EU) – Silanes are used for coupling organic polymers to inorganic materials, including pigments and fillers.
Crosslinking Agent (EU) – Selective organofunctional alkoxysilanes can react with organic polymers to provide a trialkoxysilyl group into the polymer backbone. In turn, the silane can then react with moisture to crosslink and form a three-dimensional siloxane cross-linked structure.
Dispersing Agent (EU) – Used to improve the hydrophobicity of inorganic pigments, flow and the ability to be dispersed in organic polymers and solvents.
Moisture Scavenger (EU) – In moisture sensitive formulations, the three alkoxysilane groups can scavenge water by reacting with moisture to form alcohol molecules.

To read the full article about Reactive Silanes for Enhancement of Coating Performance, click here.

Automotive Paint Product Development

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Automotive Paint Product Development & Paint Consulting

PROBLEM: A company with multibillion dollar sales to the automotive OEM market required a unique coating for markets around the globe and was unable to locate a paint company with the expertise to develop the requisite performance.

ACTION: They contacted the paint experts at Chemical Dynamics to develop a coating that would meet their performance needs of being REACH compliant, low VOC, low friction with resistant to high heat and automotive chemicals.

RESULT: It a short period of time, Chemical Dynamics was able to develop a product that met all customer requirements.

University Paint Consult/Material Evaluation

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University Paint Consult/Material Evaluation for Nano-based Additive

SITUATION: A large public university was seeking an independent paint expert opinion of possible applications for a new water based nano-based conductive additive for paint.

ACTION: The university contracted Chemical Dynamics to perform the study.

RESULT: After extensive evaluations, Chemical Dynamics was able to demonstrate that the nano-based material demonstrates the ability to replace heavy metal chrome based pigment for corrosion inhibition purposes. A second utility of the technology was determined to be as a thickener for water born coatings.

Paint Raw Material Evaluation for Global firm

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SITUATION:

A global company with multibillion dollar sales required an independent paint raw material evaluation from a paint expert of the performance and application potential of a new fluoropolymer resin that they had developed.

ACTION/RESULT:

Due to the resident coating expertise in fluoropolymer coatings, the supplier contracted Chemical Dynamics to provide an independent evaluation of this new resin chemistry. Chemical Dynamics completed the evaluation and identified multiple new applications for the fluoropolymer resin chemistry.

Hydrophobic Pigments to Avoid Flooding & Floating

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Dispersing and Wetting Hydrophobic Pigments and Fillers in Water Based Paints to avoid Pigment Flooding and Floating

A critical part of any coatings formulation is ensuring that the coating will be free of inherent defects, including pigment flooding and floating. Waterborne formulations represent some unique challenges due to multiple factors, including the high surface tension and polarity of water that does not contribute to the wetting of most pigment and filler particles. In this article, I’ll define some important considerations in formulating waterborne paints to avoid pigment flooding and floating.

Flooding, Floating, Surface Tension, Bernard Cells, Flocculation and Agglomeration

Floating describes a mottled, splotchy appearance on the surface of a paint film. It is most apparent in coatings colored with two or more pigments and is a result of the horizontal separation of different pigments. Flooding is the phenomena observed when the surface color of an applied film is uniform but is darker or lighter than it should be. This is attributed to a vertical separation of different pigments in the film.

Vertical Separation of Pigment - Horizontal Separation of Pigment — Vertical Separation Horizontal Separation

Surface Tension results when the force that occurs in a liquid at the interface differs from the forces within the liquid. Thus, surface tension is caused from the surface molecules having a higher free energy than those molecules in the bulk of the liquid.

Surface tension differential can cause a convection current resulting in a regular hexagonal surface pattern called Benard Cells. A hexagonal Benard Cell pattern results in smaller, more mobile pigment particles (smaller, less dense) being deposited on the perimeter and the less mobile particles (larger, more dense) remaining away from the perimeter.

Figure 2 – Rub-up of Flocculated Blue Pigment

Flocculation is the recombination of dispersed pigment particles that were not properly stabilized in the pigment dispersion. Flocculation is undesirable at it detracts from hiding and color development. Flocculation is reversible by applying a low degree of shear. In figure 2, the phthalocyanine (EU) blue pigment is flocculated. Upon rubbing with a finger, the deeper blue color returns.

Stabilized pigment dispersion -- Flocculated pigment dispersion — Stabilized pigment dispersion — Flocculated pigment dispersion

Pigment agglomeration is defined as pigment particles that are clumped together without sufficient vehicle or wetting agents present between pigment particles. When agglomeration occurs, extensive shear and attrition forces are usually necessary to reinstate a stabilized pigment dispersion.

To read the full article about Remedial Actions to Overcome Floating and Flooding in Waterborne Paints, click here.

Paint and Coating Failure Analysis

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CHALLENGE: A national steel company that supplies coated product to the building industry received multiple complaints that the 20 year warranted coated product they supplied showed severe dirt staining once put into service on commercial and industrial buildings.

ACTION: Chemical Dynamics as an expert paint consultant in paint failure analysis was called upon to inspect several representative building sites where samples were taken, tested and paint and coating failure analysis were conducted.

RESULT: Chemical Dynamics was able to demonstrate that the unexposed coating rapidly degraded when exposed to accelerated weathering resulting in increased susceptibility to dirt staining and loss of hardness. As a result of our analysis and testing the paint company accepted responsibility for the failures saving our client several hundred thousand dollars in claims.

Certified Green Claims Increase Value & Brand Recognition in Coatings

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Article written by Chemical Dynamics President, Ronald Lewarchik, originally published in UL Prospector.

Whether coatings are sold directly to consumers or business to business, UL’s study: Under the Lens: Claiming Green – The influence of green product claims on purchase intent and brand perception reveals that legitimate third-party, certified green claims contribute to the attractiveness of a product and command a higher price because of enhanced brand perception. The survey results are noteworthy, as 70% of Americans say they’re searching for greener products, and 67% of business decision makers indicate sustainability is an important factor when making decisions for their organizations.

Avoiding Misleading Claims

However, many manufacturers misrepresent their products by claiming they are green for the purposes of enhancing sales. In 2012, the Federal Trade Commission revised its Green Guides, the agency’s core set of guidelines to help marketers avoid making misleading environmental claims. The Guides are now more specific and prescriptive, making it easier for the FTC to prosecute “greenwashers.” Accordingly, if a green claim is considered to be deceptive in the eyes of the FTC, there is both a financial and a legal risk.

Read the full article here.

Roof Coating Analysis

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CHALLENGE:

A national distributor of painted metal roofs encountered peeling paint on several residential and public buildings. The roof coating had a 20 year warranty against peeling provided by the paint supplier, but the paint supplier failed to honor the warranty, citing a defect in the painting process rather than faulty paint. Consequently, this would have resulted in multiple law suits and multimillion dollar claims against our client.

ACTION:

As a paint consultant, Chemical Dynamics inspected multiple sites where peeling paint was evidenced, samples were taken and roof coating analysis and testing completed.

RESULT:

Chemical Dynamics was able to show that the failures were caused from faulty paint formulations that when exposed to the elements resulted in soft coatings that failed adhesion. Accordingly, our client was able shift the responsibility to the paint supplier to pay the claims.

Paint and Coating Failure Analysis

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CHALLENGE:

A century old government building, constructed of concrete, was in need of painting. Upon removal of the old paint, a reoccur-able, unpaintable powder continued to resurface on the building. The client had explored this issue with many paint companies and other paint consultants, but none of them could not explain the phenomena.

ACTION:

On short notice, Chemical Dynamics performed an onsite inspection and collected representative samples of the residue. The team performed a paint and coating failure analysis of the soluble components of the residue.

RESULT:

Chemical Dynamics was able to demonstrate that the powder residue is a result of secondary efflorescence of the concrete. Secondary efflorescence is the result of concrete degradation and the migration of water soluble salts to the surface of the concrete. With the proper diagnoses of the problem, Chemical Dynamics was able to recommend corrective action.